A new technique to suppress grating lobes beyond full wavelength element spacing for linear arrays

In the present work we present a linear array system that suppresses the development of grating lobes with inter-element spacing beyond a full wavelength. Here we deviate from using `primitive' or primary radiating elements (dipoles, slots, patches, horns, etc.) as the radiating elements of the array. Instead, we employed the array-unit element concept where the main array elements are composed of a compact sub-array unit of some primary radiating elements with the desirable radiating pattern. Using array-unit composed of dipoles as our radiating array elements, we were able to suppress grating lobes below main side-lobe level with array element spacing beyond a full wavelength. The main attraction of this technique is its exploitation of the simplicity of the uniform array analysis theory. A likely possible drawback will be mutual coupling of primary elements within the array-unit with its compact support. Indeed, the spacing between radiating elements of the array-unit are much smaller than inter-element spacing of the main array. Hence it is obvious that coupling among the elements of the array-units will be more pronounced and could be of some concern. The currently work did not account for it as it is not of major concern. It may be necessary in the future to evaluate its effect on the array pattern in order to quantify its effect on the array pattern.